Probably the next batch. This story is about a late application, but this was still in the YC S12 period: http://techcrunch.com/2012/08/18/how-instacart-hacked-yc/
A small note btw : YC is not a VC , so your line doesnt actually hold. My idea of YC was a place where you go more raw than one with traction. The eco system, the mentoring, the energy helps you iterate and fix fast, and find yourself the market fit. Its more about picking the right space by the right people, acknowledging the challenges and demonstrating that you have a vague idea on how we can tackle that.